Received signal strength based range estimation in multi-band ofdm cognitive radios

Spectrum is a precious resource and it has been underutilized according to the spectrum measurement campaigns. Cognitive Radio (CR) is one of the leading technologies for increasing the spectrum utilization efficiency. One of the approaches to utilize spectrum in CR networks is Dispersed Spectrum (DS) utilization method and this type of CR systems is called DS-CR systems. In this paper, Multi-Band OFDM waveform is considered for the utilization of spectrum efficiently in DS-CR systems. Similar to the other wireless networks, range estimation is a crucial task in the MB-OFDM based DS-CR networks. Hence, in this paper, received signal strength (RSS) based range estimation method is proposed and the fundamental limits of this method are investigated. More specifically, Cramer-Rao Lower Bound (CRLB) expression is derived. In addition, numerical results are presented to verify the analysis. The results show that adaptive ranging can be achieved by selecting appropriate number of dispersed bands in the proposed method for MB-OFDM based DS-CR networks.